A single ball valve air vent is described in U.S. Pat. No. 6,234,198 to Chalich. Such a valve has received widespread commercial acceptance and is adequate to carry out its intended purpose. However, for large sewer pipes with drainage from multiple commodes a single air flow channel may not be adequate. For this reason the search continues for more efficient air flow in air vent valves.
U.S. Pat. No. 7,140,388 to Chalich describes a dual ball valve air vent having two independent ball valves and providing multiple air flow channels.
What is needed is an air vent valve that performs as well as the single or dual ball air valve vents but utilizes a living-hinge valve to replace the ball valve(s).